Lubricating compositions



United States Patent 3,361,667 LUBRICATING COMPOSITIONS Ronald FrancisAlfred Eatly Wenhorne and David Michael Soul, London, England, assignorsto Castro] Limited, London, England, a British company No Drawing. FiledAug. 30, 1965, Ser. No. 483,833 Claims priority, application GreatBritain, Aug. 31, 1964, 35,583/64 14 Claims. (Cl. 25232.7)

ABSTRACT OF THE DISCLOSURE A lubricating composition, particularlysuitable for the lubrication of hypoid gears, which compositioncomprises a mineral lubricating oil and dissolved therein an additivecombination which confers extreme pressure properties on the compositionand which consists of (a) a chlorine-containing hydrocarbon having aboiling point or decomposition temperature of not less than 160 C.,

(b) an oil-soluble polyvalent metal salt of a dithiophosphoric acid, and

(c) a dialky phosphite,

the proportion of (a) being such as to provide from 0.42% to 6.0% byWeight of chlorine in the composition, the proportion of (b) being suchas to provide from 0.048% to 1.0% by weight of sulphur in thecomposition, and the proportion of (0) being such as to provide from0.036% to 0.3% by weight of phosphorus in the composition.

This invention is for improvements in or relating to lubricatingcompositions and is particularly concerned with lubricating compositionshaving extreme pressure properties especially suitable for thelubrication of hypoid gears, which compositions will operate underconditions of low speed and high torque as well as under conditions ofhigh speed and high load. The lubricating compositions of this inventionmay (however, be used for lubricating all kinds of industrial gears.

It is well known that under certain conditions, e.g. for the lubricationof hypoid gears, it is necessary to employ lubricants containingchemical compounds capable of reacting with metals at high temperaturesand under high pressures to form films (e.g. of iron sulphide, ironchloride or iron oxide) which prevent seizure and welding of the metalsurfaces. A variety of organic compounds have been suggested for thispurpose, including sulphur compounds of various types and containingsulphur in varying degrees of activity. It has generally been foundadvantageous to use these sulphur compounds in conjunction with leadsoaps or organic halogen compounds, or both. It is now recognised thatmany such libricants, which behave perfectly satisfactorily under normaloperating conditions and even under high loads at high speed, are notsatisfactory under conditions of high torque and low speed, e. g. forlubricating rear axles of vehicles operating in mountainous terrain.Under these conditions, certain lubricants, e.g. those containing leadsoaps or sulphur in active form, tend to cause high rates of wear or, insome cases, rippling or ridging of the gear teeth, and

to promote the rusting of ferrous metal parts in the presence ofcondensed moisture.

On the other hand lubricants which perform well under conditions of hightorque and low speed do not necessarily possess adequate load-carryingcapacity under high-speed conditions and particularly under conditionsof shock loading. In fact the two requirements have been for some timeregarded as being conflicting and British Gear Oil Specification No.CS,3000A and the now obsolete U.S. Army Specification M1LL2l02, to whichmost commonly used hypoid rear axle oils have conformed for some time,represent a compromise.

The practice among motor manufacturers for sometime past has been to uselubricants having better E.P. properties under high-speed conditionsthan the conventional MlL L2l05 oils for factory fills for passengercars. After running-in the gears for a certain period on these oils,which generally contain active sulphur and sometimes also lead soaps,the rear-axle may be drained and filled with MILL-2105 oil. Some ofthese oils, particularly those containing lead soaps, while providingadequate protection of the gears against scufiing, have been found togive rise to an undesirable amount of wear in anti-friction bearingsresulting in loss of pre-load with consequent deterioration of the gearand development of noise and other troubles. Furthermore, it is anobvious disadvantage to have different rear axle Oils for factory fillsfor passenger cars and trucks, since confusion may occure and breakdownof heavily-loaded truck axles might take place under low-speedhigh-torque conditions if lubricated with an oil of the wrong type.

It is clearly desirable that hypoid gear Oils used for factory fillsshould be compatible with hypoid gear oils used subsequently after therunning-in process has been completed. It is, therefore, advantageous ifthe same additives are present in the oil used for factory fills as inthe oil subsequently purchased from a garage and used either fortopping-up or defilling the axle housing after draining. The additivecombination of the present invention has the advantage that it may beused both for factory fill purposes and at a lower dosage level forgeneral use in which case no problems due to incompatibiity will beencountered.

Recent improvements in engine designs have led to increased power outputand this, combined With the tendency to increase the hypoid pinionoffset, has brought about a very considerable increase in the severityof the operating conditions of the gears of passenger cars. The loadingon truck axles has also increased and the high speeds at which manyvehicles, particularly military vehices, operate combined with the heavyloads carried have exposed the limitations of MILL-2105 oils both underhigh-speed conditions of operation and under lowspeed high torqueconditions.

In addition to having adequate extreme pressure properties, a universalhypoid axle lubricant must be relatively non-corrosive to cuprous metalsat high operating temperatures and must provide adequate resistance tothe corrosion of ferrous metals in the presence of water.

To obtain a satisfactory oil for first fill purposes, it is highlydesirable that axle tests should be passed both under high speed/highload conditions and under low speed high torque conditions. It hasgenerally been considered b that a compound containing a fair quantityof fairly active sulphur is necessary together with chlorine to pass theformer type of test, Whilst phosphorus compounds are required to passthe latter type of test.

A surprising feature of the present invention is that both requirementscan be satisfied by using relatively small amounts of two readilyavailable and inexpensive phosphorus compounds in conjunction with achorine compound. Furthermore, these compounds are freely oil solubleand without corrosive attack on copper at temperatures up to 135 C.

According to the present invention there is provided a lubricatingcomposition comprising a mineral lubricating oil and dissolved thereinan additive combination which confers extreme pressure properties on thecomposition and which consists of (a) a chlorine-containing hydrocarbonhaving a boiling point or decomposition temperature of not less than 160C.,

(b) an oil-soluble polyvalent metal salt of a dithiophosphoric acid, and

(c) a dialkyl phosphite.

Where the lubricating compositions are for use specifically as hypoidgear lubricants, it is preferred that the total chlorine content is from2.5% to 6.0% by Weight, the proportion of (b) is such as to provide from0.2% to 1.0% 'by weight of sulphur in the composition, and theproportion of (c) is such as to provide from 0.1% to 0.3% by Weight ofphosphorus in the composition. The proportion of (b) is preferably suchas to provide from 0.3% to 0.7% by Weight of sulphur in the composition.

Examples of additive (a) are:

Chlorinated parafiin wax,

Chlorinated kerosine,

Hexachlorethane,

Benzene hexachloride,

Chlorinated indenes, Dichlordiphenyltrichlorethane (DDT) and Chlorinateddiphenyls.

Examples of additive (b) are:

Zinc di-n-pentyl dithiophosphate Zinc di(l,3 dimethylbutyl)dithiophosphate Zinc isopropyl/ 1,3 dimethyl butyl dithiophosphateZinc isobutyl/a-myl dithiophosphate Zinc diamyl dithiophosphate derivedfrom mixed amyl alcohols Zinc dialkyl dithiophosphate derived from mixedstraight chain -0 alcohols Zinc dialkyl dithiophosphate derived frommixed C -C alcohols Nickel di(2-ethyl hexyl)dithiophosphate Barium dilauryl dithiophosphate Chromium di(p-octylphenyl) dithiophosphateExamples of additive (c) are:

Diethyl phosphite,

Di-isopropylphosphite Di-n-butylphosphite,

Dioctyl phosphite,

Dilauryl phosphite.

These phosphites have the formula:

where R and R are the same or different alkyl groups. Preferably R and Rtogether have a total of from 3 to 12 carbon atoms.

Additive (a) is preferably a parafiin wax containing from 40 to 70% ofchlorine, additive (b) is preferably a zinc dialkyl-di thiophosphatewherein each alkyl group contains from 3 to 12 carbon atoms and additive(c) is preferably di-isopropyl phosphite.

It is to be understood that the composition may contain conventionallubricating oil additives, for example, antioxidants or corrosioninhibitors, dispersants, detergents, pour point depressants and V1.Improvers.

A corrosion inhibitor which is particularly useful in the compositionsof the present invention is on oil-soluble basic alkaline earth metalsulphonate which may or may not be neutralized with a Weak acid, e.g.carbon dioxide and is preferably employed in an amount of at least 0.05%and more preferably in an amount from 0.1 to 0.5% by weight of the totalcomposition.

Examples of these additives are:

Basic barium petroleum sulphonate,

Basic calcium petroleum sulphonate,

Basic strontium petroleum sulphonate,

Basic barium dinonyl naphthalene sulphonate, and, Basic barium didodecylor octadecyl benzene sulphonate.

Any of these compounds may be neutralized wholly or in part with CO togive the corresponding carbonate complex.

Another additive which is particularly usefulin this invention is theadditive prepared by reacting a phosphosulphurised polyisobutylene withbarium hydroxide in the presence of an alkyl phenol, carbonating andfurther reacting with a basic alkaline earth metal sulphonate.

The invention also includes an additive combination for conferringextreme pressure properties to a mineral oil lubricant, whichcombination comprises from 67% to 74% of a chlorinated paraffin waxcontaining from 40% to 70% by weight of chlorine, from 15% to 20% of azinc dialkyl dithiophosphate having from 3 to 12 carbon atoms in eachalkyl group, and from 4.8% to 5.5% of a dialkyl phosphite having a totalof from 3 to 12 carbon atoms per molecule, the percentages being byweight on the total weight of addition. The dialkyl phosphite ispreferably diisopropyl phosphite.

The combination may also with advantage contain from 6% to 8% of aphosphosulphurised polyisobutylene reacted with a barium alkyl phenateand over-based with a basic barium petroleum sulphonate as a detergent,and from 0.6% to 0.8% of a co-polymer of mixed fatty acid methacrylatesas a pour point depressant. Reference is made to US. Patent No.2,969,324 for further description of the phosphosulphurized detergents.

These additive combinations may be supplied either near or as oilconcentrates for dilution to the extent required for the particularlubricating job for which they are to be used.

A representative lubricating composition of the invention consistsessentially of a mineral lubricating oil having dissolved therein from5% to 15% of a chlorinated paraifin wax containing from 40% to 70% byweight of chlorine, from 1.5% to 3.5% of a zinc dialkyl dithiophosphatehaving from 3 to 12 carbon atoms in each alkyl group, from 0.5 to 1.0%of a dialkyl phosphite having from 1 to 6 carbon atoms in each alkylgroup, from 0.5% to 2% of a phosphosulphurized polyisobutylene reactedwith a barium alkyl phenate and over-based with a basic barium petroleumsulphonate and from 0.05% to 0.2% of a co-polymer of mixed fatty acidmethacrylates, all percentages being by weight on the Weight of thecomposition.

Following is a description by way of example of typical compositions ofthe present invention.

EXAMPLE I Percent Mineral oil A 44.0

Mineral oil B 41.65

Percent Chlorinated parafiin wax containing about 42% chlorine 10.0 Zincisopropyl/ 1,3 dimethyl butyl dithiophosphate 2.5 Detergent D 1.0Di-isopropyl phosphite 0.75 Pour Point Depressant A 0.1

Mineral oil A was a high viscosity, Western bright stock, having aviscosity of about 800 seconds Redwood I bright stock at 140 F.

Mineral oil B was a solvent refined mineral oil of viscosity about 150seconds Redwood I at 140 F.

The zinc dithiophosphate was in the form of an approximately 80%concentrate in oil, the phosphorous content of the concentrate beingapproximately 8%. The detergent D was a phosphosulpliurizedpolyisobutylene reacted with a barium alkyl phenate and overbased with abasic barium petroleum sulphonate. The pour point depressant A was acopolymer of mixed fatty acid methacrylates.

This composition possessed the following viscosity characteristics:

The composition gave good results when subjected to a relatively severeroad test in the hypoid rear axle of a motor vehicle.

EXAMPLE II Percent Mineral oil A 39.5

Mineral oil B 46.15 Chlorinated parafiin wax containing 42% chlorine10.0 Zinc isobutyl/amyl dithiophasphate 2.5 Di-isopropyl phosphite 0.75Detergent D 1.0 Pour pont depressant 0.1

The zinc dithiophosphate wa in the form of an approximately 80%concentrate in oil, the phosphorus content of the concentrate beingabout 8.0%.

In order to test the properties of these compositions that of Example Iwas run in the rear axle of a high performance 2 litre saloon car underhigh speed conditions, together with braking tests, these tests beingcarried out in the Alps over a total distance of approximately 5000miles. Identical tests were carried out on an identical vehicle using awell-known prior art hypoid gear oil (Blend A) containing 5.5% of anExtreme pressure additive containing about 16% sulphur, 3% Zn, 3% P and16.5% C1, and 0.05% pour point depressant. This particular type ofvehicle was chosen since the cooling air flow normally experienced bythe rear axle had been greately reduced due to the design of the axleunit, which was partly housed in a well in order to accommodate thesuspension unit. Consequently the rear axle tended to run at highertemperatures than normal, these temperatures being greatly increasedunder heavy braking conditions by conduction from the disc brakes alongthe drive shafts to the axle casing.

The extreme pressure properties of both the prior art oil and thecomposition of the present invention (Example I) were examined beforeand after test by testing on the well-known Four-ball Machine, similarto that described by Boerlage in Engineering July 13, 1933, volume 136,page 46. This apparatus comprised four steel balls arranged in the formof a pyramid. The top ball was held in a chuck attached to a spindlerotating at approximately 1500 rev./min. and pressed against the threebottom balls clamped in a stationary ball-holder. The balls wereimmersed in the oil to be tested. Tests were normally run for one minuteat a series of diflFerent loads. The results of these tests are given inTable I.

The surprising effect was that the composition of the present inventionwas more efiicient after test than before particularly with regard tothe load at incipient seizure.

Although the above test showed that a typical composition of the presentinvention was efiioient under rigorous conditions involving high speedoperation with braking, it was felt that more controlled conditionscould be obtained by carrying out tests on a tesbtrack.

Accordingly another model of the same vehicle was fitted with a rearaxle which had been previously run-in. Thermocouples were attached tothe drain plug in order to measure the bulk oil temperature, to thebearing assembly in order to measure the temperature of the shaft andthe gear in general, and to the inspection cover in order to measure thetemperature of the oil jet leaving the teeth of the gear. Thethermocouples were connected via a switch mechanism to a recording headfitted in the car. The cold junction was also located in the car andconsequently all temperature readings had to be adjusted to thetemperature ambient in the car. In order to prevent loss of heat fromthe forward end of the axle a fibreglass/ asbestos lagging was wrappedaround the housing at the nose end. The car towed a dynamometer by meansof a draw bar. The load imposed was continuously adjustable from withinthe car by means of an electronic control, so enabling absolute controlover the load to be maintained.

Four test sequences were devised in order to obtain a bulk oiltemperature of about 150 C. These are given in Table II.

TABLE II.TESI SEQUENCES FOR DYNAMOMEIER Sequence Load (1135.) on CarGear Car Speed,

Draw Bar m.p.h.

Tests were carried out in the following order:

(1) Fresh Blend A, sequence 1, 3 and 4. Allowed to cool to ambient(approximately 1 hours), then run at normal road speed for 10 minutes.

(2) Used Blend A, sequence 1, 3 and 4.

(3) Fresh composition of Example II, sequence 1 and 2.

(4) Used composition of Example II, sequence 1 and 2.

The results of these tests are given in Table III.

The results obtained on the two oils are given below.

All runs were conducted in similar climatic conditions of dry, Warmweather with light winds.

These results-showed clearly that the composition of the presentinvention allowed the rear-axle to run at a much lower temperature thanthe prior art hypoid gear oil. Furthermore, the load which had to beapplied to cause the oil to reach a temperature of about 150 C., wasvery much higher than in the case of the prior art gear oil. This isshown by the fact that sequence 2 was much more severe than eithersequence 3 or sequence 4, in fact so severe that undue strain was placedon the dynarnometer, the engine of the car and on components notconnected with the axle..

Four-ball tests were again carried 'out on Blend A before and after testand the composition of Example 11 as used in the above dynamometer testsand here again the improved extreme pressure properties of thecomposition according to the present invention after use weredemonstrated, the results of these tests being given in Table IV.

Example Blend B Spec.

II Required 21. 49 17. 29 28. 61 30. 19 33. 1 74. 6 100% max. Acid No.of oil after test. 3.06 7. 2 None. Pentane insolubles, percent".-. 3. 396.09 3% max. Benzene insolubles, percent 2. 07 2. 72 2% max. Catalystweight loss (g.) 0. 44 2. 21 Report. Gear back lash (inches) 0.00050.002 Do. Bearing clearance (inches) 0.0005 0.0005 Do.

The results indicated that the performance of Example 11 was asignificant improvement over that of Blend B, a typical MIL-L-2105lubricant.

We claim:

1. A lubricating composition consisting essentially of a minerallubricating oil having dissolved therein an additive combination whichconfers extreme pressure prop- TABLE IV Load kg. at Weld Scar diameter(mm) at load in kg. of

incipient pt.

seizure (kg) Blend A:

Before test 120/130 400 1. 20 1.56 1. 61 2. 17

After test 120/135 310 l. 34 1. 64 1. 71 1. 78 2.13 Composition ofExample II:

Before test 160/165 350 0.58 1. 73 1. 98 2. 2

After test 195/200 400 0. 89 1. 02 1. 62 2. 0

In order to evaluate the oxidation stability of a typical composition inaccordance with the invention, Example II was compared with a blend(Blend B) containing the same additive package as Blend A but in ahigher concentration (9.5%). The test chosen was that laid down in US.Military Specification MI-L-2105B. In this test a small gear box is runfor hours at a controlled temperature, the gears being lubricated by theoil under test. At the end of the alloted time the oil is examined forviscosity increase and insolubles content.

The test is fully described in Federal Test Method Std-191, method2504T, the conditions of test being as follows:

Temperature 325 F.i1 F. (l57.2 C.i0.6 C.).

Load on gears provided by driving an electric generator to give anoutput of 128 watts.

Air flow through lubricant 1.11 litres per hour.

As well as the steel gears a copper catalyst was included in the systemto determine the copper activity of the lubricant.

erties on the composition and which consists of (a) achlorine-containing aliphatic hydrocarbon having a boiling point ordecomposition temperature of not less than C. selected from the grouponsisting of chlorinated paraffin wax, chlorinated kerosine,hexachlorethane, benzene hexachloride, chlorinated indenes,clichlordiphenyltrichlorenthane and chlorinated diphenyls;

(b) an oil-soluble polyvalent metal salt of a dialkyl dithiophosphoricacid wherein each alkyl group contains from 3 to 12 carbon atoms; and

(c) a dialkyl phosphite having a total of from 2 to 12 carbon atoms inthe alkyl group, the proportion of (a) being such as to provide fromabout 2.5% to 6.0% by weight of chlorine in the composition, theproportion of (b) being such as to provide from about 0.2% to 1.0% byweight of sulphur in the composition, and the proportion of (c) beingsuch as to provide from about 0.1% to 0.3% by weight of phosphorus inthe composition.

2. A lubricating composition as claimed in claim 1 wherein theproportion of (b) is such as to provide from 0.3% to 0.7% by weight ofsulphur in the composition.

3. A lubricating composition as claimed in claim 1 wherein (a) is aparafiin wax containing from 40% to 70% by Weight of chlorine.

4. A lubricating composition as claimed in claim 1 wherein thepolyvalent metal of (b) is zinc.

5. A lubricating composition as claimed in claim 1 wherein (c) isdi-isopropyl phosphite.

6. A lubricating composition as claimed in claim 1 wherein there is alsopresent at least 0.05% by Weight of an oil-soluble basic alkaline earthmetal sulphonate.

7. A lubricating composition as claimed in claim 6 wherein there ispresent fr rn 0.1% to 0.5% by Weight of the oil-soluble basic alkalineearth metal sulphonate.

8. A lubricating composition as claimed in claim 6 wherein theoil-soluble basic alkaline earth metal sulphonate is wholly or partiallyneutralised with carbon dioxide to give the corresponding carbonatecomplex.

9. A lubricating composition consisting essentially of a minerallubricating oil having dissolved therein from to of a chlorinatedparafiin Wax containing from 40% to 70% by weight of chlorine, from 1.5%to 3.5% of a zinc dialkyl dithiophosphate having from 3 to 12 carbonatoms in each alkyl group, from 0.5% to 1.0% of a dialkyl phosphitehaving from 1 to 6 carbon atoms in each alkyl group, from 0.5% to 2% ofa phosphosulphurised polyisobutylene reacted with a barium alkyl phenateand over-based with a basic barium petroleum sulphonate and from 0.05%to 0.2% of a co-polymer of mixed fatty acid methacrylates, allpercentages being by Weight on the Weight of the composition.

10. An additive combination for conferring extreme pressure propertiesto a mineral oil lubricant, which combination consists essentially offrom 67% to 74% of a chlorinated parafiin wax containing from to byweight of chlorine from 15% to 20% of a zinc dialkyl dithiophosphatehaving from 3 to 12 carbon atoms in each alkyl group, and

from 4.8% to 5.5% of a dialkyl phosphite having a total of from 3 to 12carbon atoms per molecule, the percentages being by weight on the totalWeight of the combination.

11. An additive combination as claimed in claim 10 wherein the dialkylphosphite is di-isopropyl phosphite.

12. An additive combination as claimed in claim 10 containing from 6% to8% of a phosphosulphurised polyisobutylene reacted with a barium allcylphenate and over-based with a basic barium petroleum sulphonate as adetergent.

13. An additive combination as claimed in claim 10 containing from 0.6%to 0.8% of a co-polymer of mixed fatty acid methacrylates as a pourpoint depressant.

14. An additive combination as claimed in claim 10 in solution in amineral lubricating oil.

References (Iited UNITED STATES PATENTS 2,285,855 6/1942 Downing et al.25249.8 3,001,939 9/1961 OHalloran 25232.7 3,013,971 12/1961 Mastin25232.7 3,029,268 4/1962 Goldsmith 252-327 X 3,053,766 9/1962 Munsell etal. 252-32] DANIEL E. WY MAN, Primary Examiner. PATRICK P. GARVIN,Examiner.

